The high fidelity industry has long recognized the importance and need of a long lasting, high performance, easy to install power distribution products that can handle the enormous demands a vehicle stereo system places on a power distribution system. Such power systems not only must exceed the standards of high performance and reliability, they must be simple to manufacture and inexpensive to produce.
Conventional power distribution devices however are limiting at best. They are inadequately engineered for true high current carrying demands. Typically, these systems are large in size and often require assembly. This makes installation more time consuming and difficult, especially where space is limited.
Typically, conventional devices are usually manufactured in the shape of a rectangle or square from a square stock, i.e., square bar. When machining the square stock, the threaded holes are drilled in the ends of the square stock. However, in order to properly drill the threaded holes in the sides of the square stock and to chamfer all of the edges, the square stock must be taken off of the machine to accomplish this task. For economy as well as ease of manufacturing, it is desirable for manufacturers to have a design that allows some of the machining to be automated on one machine such as a screw or computer numerical control (CNC) machine. A traditional square design requires more interface or human handling. In addition, it is desirable to have a design that requires less metal to manufacture. The additional metal is more costly and it does not improve the overall power distribution of the device.
The conventional devices have other disadvantages. First, some fail to obtain a high integrity electrical connection. That is, the connection between the wire conductors and the power distribution device is not secure. When a wire conductor is inserted in an opening in the device, its strands (up to 1000 or more in a 4 gauge cable) lay flush on a flat or indented spherical surface. The wire is secured to the device by a screw which clamps down on the strands of the wire conductor. Typically, the screw contains a flat head for this connection.
Since the strands of the wire are held in place by the force of the flat head against the conductor, some strands are spread away from the bundle and other strands never even contact the screw entirely. That is, the contact force is large but makes minimal surface contact. When the device vibrates or moves as a result of vehicle movement, e.g., a bump, etc., the individual strands of the wire will move farther away from the bundle of strands around the edge of the screw. This decrease in the integrity of the connection results in a voltage drop due to the build up from increased contact resistance. In addition, the wire conductors may eventually fully separate from the power distribution device.
The quality of the stereo system will not only decrease as a result of a known large voltage drop because of the poor connection but because such a voltage drop will not satisfy the standards of the International Auto Sound Challenge Association (IASCA). This association sets standards for which automobile owners/dealers must comply in order to enter their cars in automobile shows.
IASCA's rules dictate a maximum allowable voltage drop from the connection of the battery to the amplifier located in the rear of the car. The voltage drop cannot exceed 0.5 volts. IASCA sets this voltage drop at 0.5 volts so that the amplifier will operate at an optimal level. That is, since the amplifier undergoes deep transients as in sudden calls for deep bass tones, it will require high current inrushes. The resultant large voltage drop caused by contact resistance can cause an amplifier to be less efficient.
Other conventional devices obtain secure connection using an external compressible sleeve surrounding a stranded wire conductor. U.S. Pat. No. 902,235 to Kellner shows on example of this type of device. However, manufacturing the sleeve increases cost and does not improve the ultimate contact between the stranded wires and the connector surface. In addition, the collet or sleeve often cannot be reused once it is accessed.
A second disadvantage of the conventional power distribution devices is that they are open to wear and abrasion as a result of the outside conditions in the vehicle. Most do not have a strong abrasion free housing to prevent dirt from accumulating on the wire connections on the device. Such a housing can prevent significant power loss by preventing such dirt from accumulating on the connection areas of the device. U.S. Pat. No. 4,050,770 shows a junction box for terminating electrical power conductors. However, in order to fasten the wire conductors to the junction terminals, the entire housing is exposed to the outside environment. Consequently, dirt and oil from the vehicle accumulates on the open connection areas.
A third disadvantage of the conventional power distribution devices is their height. Most installers require the lowest profile distributor for aesthetic reasons as well as IASCA rules.
Accordingly, it is an object of the present invention to provide a power distribution device for use in vehicle stereo systems which solves the aforementioned problems.